There are known in the prior art "schnabel" or multiple span bolster cars for the transport of extremely heavy and large pieces of equipment such, for example, as large electrical transformers. Other pieces to be conveyed by such special cars would, for example, be extremely large steel sections of a bridge, or the like. These cars are made up of two halves, each of which includes a generally triangular beam pivotally supported on an upper span bolster which in turn is supported on one or two lower span bolsters. In normal use of the schnabel car arrangement when carrying a load, the lower ends of each of the triangular beams support hinges which couple the beams to the load support. The upper ends of the beams are provided with compression jacks. When the schnabel car is not being used to convey a load, the two halves usually are coupled together in some manner so as to permit the assembly to be transported empty to the site or location at which it is to receive a load.
In the course of movement of a train, the car units thereof are subjected at times to extremely heavy tension and compressive forces which may be termed draft and buff forces. These forces may, for example, be of the order of 600,000 to 1,200,000 pounds in the direction of the length of the unit. While such loads do not cause any serious problems with cars which are coupled together in the ordinary manner, they do create serious problems in the case of multiple span bolster car arrangements. For example, if the two halves of an empty schnabel car arrangement are coupled by connecting the beams and the thus assembled unit makes up part of a train, compressive forces must be transmitted from the outboard coupling through the first outboard half upper span bolster and through the first half beam pivot to the first schnabel beam. From the first schnabel beam, the force is transmitted to the second schnabel beam down through the second beam pivot to the second half upper span bolster and, finally, to the coupling on the second half outboard truck. It will readily be appreciated that the line or lines along which the forces are transmitted through the beams are considerably above the line of application of the force between couplings. As a result of this fact, there is produced a force tending to lift the inboard end of the upper bolster and thus the lower span bolster and its associated trucks off the track. Such a force clearly greatly increases the possibility of the occurrence of a derailment. Of course, usually when the schnabel car is carrying a full load, sufficient weight is applied to the beams to inhibit this occurrence.
In addition to the condition described above, in connection with the compressive forces applied to a multiple span bolster car arrangement, in any multiple span bolster car arrangement there is a considerable distance between the point at which a coupler or a drawbar is pivoted to the lower span bolster and the point at which the upper span bolster load is applied to the lower span bolster. It will further readily be appreciated that, if any misalignment between these two points exists, the relatively heavy compressive forces applied to the unit at times can induce jackknifing and resultant derailment.
I have invented an improved multiple span bolster car arrangement which overcomes the defects of multiple span bolster car arrangements of the prior art. My improved multiple span bolster car arrangement inhibits derailment of any of the trucks of the unit as a result of compressive forces applied thereto. My arrangement greatly facilitates the safe transportation of two empty schnabel car halves. My improved multiple span bolster car arrangement substantially reduces the possibility of derailment as a result of jackknifing. My arrangement is relatively simple in construction for the result achieved thereby.
My inboard coupling assembly also takes care of draft (tension) forces which can also be a problem if eccentricity between the center line of the coupler and the reaction of the car body is too large.
Another advantage of my inboard coupling arrangement is that it reduces the amount of lateral clearance necessary to accommodate two schnabel halves being transported in the manner known to the prior art as, for example, when a curve is being negotiated.